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1978 Ih 686 d312 gear drive starter questions


IHFAN21
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I'm almost certain you need a twelve tooth. I run into starter problems literally every time I get a reman from case IH. Same with alternators. One might be great and last forever, the other barely makes it two months, or it's completely clocked wrong or doesn't even fit. 

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5 minutes ago, MinnesotaFarmall said:

I'm almost certain you need a twelve tooth. I run into starter problems literally every time I get a reman from case IH. Same with alternators. One might be great and last forever, the other barely makes it two months, or it's completely clocked wrong or doesn't even fit. 

I’m pretty sure your right I’m at least hoping that fixes it I don’t know when I get to getting another starter but I can promise you all I won’t leave you hanging an I’ll let you know what does solve the problem 

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pretty certain in that a hydro starter nose cone  will not  inter change with the gear drive diesels.  The ring gear application chart will also help you sort out possibility's,  the gear drive ring gear will not go on a hydro flywheel

  Hydro ring gear, it will interchange with some if not all of the gas gear drives therefore the starter 10 tooth will do the same.

And if I remember correctly a hydro ring gear set 1/4 inch closer (forward) to the engine than the gear drive,

 

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I should have presented my point better, I am pretty positive you will not take a stock starter out of a diesel hydro of that series of tractors and get it to work in a gear drive diesel of either engine (312-310) persuasion. I am sure that the diesel hydro and the gas gear drives starters will fit in most tractors of that series that fit the category's.  And if you go to A&I and look at the ring gear application guide that shows diameters and tooth counts its pretty easy to figure out. There are reman starter places that are misstating what they fit.

Its logical that a larger ring gear outer diameter needs a smaller diameter bendix gear, but more or less teeth  does not always reflect diameter.  And if driving off center from the starter "hole" in the center housing it really complicates things.

Thats why finding one that is working and testing it on the "problem child" is your best option in this situation.

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On 12/2/2021 at 8:17 AM, Farmall Doctor said:

When I put my 686D gear drive together I couldn't find a starter. I used the old Hydro 30MT starter and ordered a new nose cone and bendix for the gear drive. I had to grind a flat spot on the starter housing to make it fit the TA housing. 

IMG_20211202_0905543.jpg

So hey is your tractor a d312 gear drive correct? If so am I understanding you correct you bought a 30mt off a hydro changed nose cone and drive to gear tractor with 12 teeth?

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2 hours ago, Farmall Doctor said:

My tractor was a demolished Hydro. (Migrant workers tried to tow start it). D312, just like you said that you are looking for. I told the starter shop what I needed to do and we built it. I just had to grind the flat spot to make the body fit the TA housing. 

So honestly if I bought a 12 tooth starter do you think it would work and be fine? @farmalldoctor

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Guess what?! I found the invoice! Nose cone part number 35640-1010

                                                         Bendix drive part number 3-276

Hopefully these numbers will work for a starter shop to find what you need.

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a little google-fu and it looks like the 3-276 is a 12T. Only place I could find it was on a starter supply site in Mexico, but:

Bendix 3-276

None
  • SPECS:12-T, CCW, 3-SPL
  • SPECS for:Delco 30MT Series DD Starters
  • DIM 1:14.3mm ID, 36.3mm Gear OD, 96.5mm OAL
  • FEATURE 1:Accurate rebuilt - sold outright
 
Inventario : 0
SKU #3-276
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